This invention relates to an automatic developing apparatus for developing a photosensitive material such as a photo film and a photographic paper by passing the photosensitive material through a treatment tank filled with a processing liquid.
Conventionally, an automatic developing apparatus for a photosensitive material (hereinafter referred to as an auto-developing-apparatus) comprises a plurality of treatment tanks, each of them filled with a processing liquid; a supply unit for supplying a water or the processing liquid to adjust a concentration of the processing liquid in the treatment tank; and a waste liquid tank for storing the waste liquid from the treatment tank due to the supply of the processing liquid or the water to the treatment tank. In this auto-developing-apparatus further comprises an alarm for generating a sound to notify an operator when the liquid level in the waste liquid tank reaches a predetermined level. Upon being notified by the alarm, the operator instructs the auto-developing-apparatus to stop its operation so as to prevent the waste liquid tank from overflowing and at the same time discharges the waste liquid from the waste liquid tank. After the discharging the waste liquid from the waste liquid tank is done, the operator commands a resume of the operation of the auto-developing-apparatus for resuming the development operation.
However, in the above described auto-developing-apparatus, it is not necessarily the case that the operator always instructs the halting of the operation of the auto-developing-apparatus at the time of alarm going off. In fact if the operator inadvertently forgets to give the command to halt the operation of the auto-developing-apparatus, the waste liquid overflows from the waste liquid tank. In order to cope with this human dependent alarm system, it is possible to include a CPU of a controller that controls the supplying operation of the supply unit when the liquid level in the waste liquid tank reaches a predetermined level. However, even with this countermeasure, there exists a possibility of malfunction of the controller due possibly to an external noise and an instantaneous power failing situation, leading to a continuous supply of the liquid to the treatment tank by the supply unit, resulting in overflowing the waste liquid from the waste liquid tank.
In view of the above, there is certainly room for improvement in designing the auto-developing-apparatus that enables a secure prevention of overflowing of the waste liquid from the waste liquid tank.